x86/xen: resume timer irqs early
[linux/fpc-iii.git] / kernel / panic.c
blobb6c482ccc5db77f4af0afbb0948ff0373bb094d5
1 /*
2 * linux/kernel/panic.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 /*
8 * This function is used through-out the kernel (including mm and fs)
9 * to indicate a major problem.
11 #include <linux/debug_locks.h>
12 #include <linux/interrupt.h>
13 #include <linux/kmsg_dump.h>
14 #include <linux/kallsyms.h>
15 #include <linux/notifier.h>
16 #include <linux/module.h>
17 #include <linux/random.h>
18 #include <linux/ftrace.h>
19 #include <linux/reboot.h>
20 #include <linux/delay.h>
21 #include <linux/kexec.h>
22 #include <linux/sched.h>
23 #include <linux/sysrq.h>
24 #include <linux/init.h>
25 #include <linux/nmi.h>
27 #define PANIC_TIMER_STEP 100
28 #define PANIC_BLINK_SPD 18
30 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
31 static unsigned long tainted_mask;
32 static int pause_on_oops;
33 static int pause_on_oops_flag;
34 static DEFINE_SPINLOCK(pause_on_oops_lock);
36 int panic_timeout;
37 EXPORT_SYMBOL_GPL(panic_timeout);
39 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
41 EXPORT_SYMBOL(panic_notifier_list);
43 static long no_blink(int state)
45 return 0;
48 /* Returns how long it waited in ms */
49 long (*panic_blink)(int state);
50 EXPORT_SYMBOL(panic_blink);
53 * Stop ourself in panic -- architecture code may override this
55 void __weak panic_smp_self_stop(void)
57 while (1)
58 cpu_relax();
61 /**
62 * panic - halt the system
63 * @fmt: The text string to print
65 * Display a message, then perform cleanups.
67 * This function never returns.
69 void panic(const char *fmt, ...)
71 static DEFINE_SPINLOCK(panic_lock);
72 static char buf[1024];
73 va_list args;
74 long i, i_next = 0;
75 int state = 0;
78 * Disable local interrupts. This will prevent panic_smp_self_stop
79 * from deadlocking the first cpu that invokes the panic, since
80 * there is nothing to prevent an interrupt handler (that runs
81 * after the panic_lock is acquired) from invoking panic again.
83 local_irq_disable();
86 * It's possible to come here directly from a panic-assertion and
87 * not have preempt disabled. Some functions called from here want
88 * preempt to be disabled. No point enabling it later though...
90 * Only one CPU is allowed to execute the panic code from here. For
91 * multiple parallel invocations of panic, all other CPUs either
92 * stop themself or will wait until they are stopped by the 1st CPU
93 * with smp_send_stop().
95 if (!spin_trylock(&panic_lock))
96 panic_smp_self_stop();
98 console_verbose();
99 bust_spinlocks(1);
100 va_start(args, fmt);
101 vsnprintf(buf, sizeof(buf), fmt, args);
102 va_end(args);
103 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
104 #ifdef CONFIG_DEBUG_BUGVERBOSE
106 * Avoid nested stack-dumping if a panic occurs during oops processing
108 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
109 dump_stack();
110 #endif
113 * If we have crashed and we have a crash kernel loaded let it handle
114 * everything else.
115 * Do we want to call this before we try to display a message?
117 crash_kexec(NULL);
120 * Note smp_send_stop is the usual smp shutdown function, which
121 * unfortunately means it may not be hardened to work in a panic
122 * situation.
124 smp_send_stop();
127 * Run any panic handlers, including those that might need to
128 * add information to the kmsg dump output.
130 atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
132 kmsg_dump(KMSG_DUMP_PANIC);
134 bust_spinlocks(0);
136 if (!panic_blink)
137 panic_blink = no_blink;
139 if (panic_timeout > 0) {
141 * Delay timeout seconds before rebooting the machine.
142 * We can't use the "normal" timers since we just panicked.
144 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
146 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
147 touch_nmi_watchdog();
148 if (i >= i_next) {
149 i += panic_blink(state ^= 1);
150 i_next = i + 3600 / PANIC_BLINK_SPD;
152 mdelay(PANIC_TIMER_STEP);
155 if (panic_timeout != 0) {
157 * This will not be a clean reboot, with everything
158 * shutting down. But if there is a chance of
159 * rebooting the system it will be rebooted.
161 emergency_restart();
163 #ifdef __sparc__
165 extern int stop_a_enabled;
166 /* Make sure the user can actually press Stop-A (L1-A) */
167 stop_a_enabled = 1;
168 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
170 #endif
171 #if defined(CONFIG_S390)
173 unsigned long caller;
175 caller = (unsigned long)__builtin_return_address(0);
176 disabled_wait(caller);
178 #endif
179 local_irq_enable();
180 for (i = 0; ; i += PANIC_TIMER_STEP) {
181 touch_softlockup_watchdog();
182 if (i >= i_next) {
183 i += panic_blink(state ^= 1);
184 i_next = i + 3600 / PANIC_BLINK_SPD;
186 mdelay(PANIC_TIMER_STEP);
190 EXPORT_SYMBOL(panic);
193 struct tnt {
194 u8 bit;
195 char true;
196 char false;
199 static const struct tnt tnts[] = {
200 { TAINT_PROPRIETARY_MODULE, 'P', 'G' },
201 { TAINT_FORCED_MODULE, 'F', ' ' },
202 { TAINT_UNSAFE_SMP, 'S', ' ' },
203 { TAINT_FORCED_RMMOD, 'R', ' ' },
204 { TAINT_MACHINE_CHECK, 'M', ' ' },
205 { TAINT_BAD_PAGE, 'B', ' ' },
206 { TAINT_USER, 'U', ' ' },
207 { TAINT_DIE, 'D', ' ' },
208 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
209 { TAINT_WARN, 'W', ' ' },
210 { TAINT_CRAP, 'C', ' ' },
211 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
212 { TAINT_OOT_MODULE, 'O', ' ' },
216 * print_tainted - return a string to represent the kernel taint state.
218 * 'P' - Proprietary module has been loaded.
219 * 'F' - Module has been forcibly loaded.
220 * 'S' - SMP with CPUs not designed for SMP.
221 * 'R' - User forced a module unload.
222 * 'M' - System experienced a machine check exception.
223 * 'B' - System has hit bad_page.
224 * 'U' - Userspace-defined naughtiness.
225 * 'D' - Kernel has oopsed before
226 * 'A' - ACPI table overridden.
227 * 'W' - Taint on warning.
228 * 'C' - modules from drivers/staging are loaded.
229 * 'I' - Working around severe firmware bug.
230 * 'O' - Out-of-tree module has been loaded.
232 * The string is overwritten by the next call to print_tainted().
234 const char *print_tainted(void)
236 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
238 if (tainted_mask) {
239 char *s;
240 int i;
242 s = buf + sprintf(buf, "Tainted: ");
243 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
244 const struct tnt *t = &tnts[i];
245 *s++ = test_bit(t->bit, &tainted_mask) ?
246 t->true : t->false;
248 *s = 0;
249 } else
250 snprintf(buf, sizeof(buf), "Not tainted");
252 return buf;
255 int test_taint(unsigned flag)
257 return test_bit(flag, &tainted_mask);
259 EXPORT_SYMBOL(test_taint);
261 unsigned long get_taint(void)
263 return tainted_mask;
267 * add_taint: add a taint flag if not already set.
268 * @flag: one of the TAINT_* constants.
269 * @lockdep_ok: whether lock debugging is still OK.
271 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
272 * some notewortht-but-not-corrupting cases, it can be set to true.
274 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
276 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
277 printk(KERN_WARNING
278 "Disabling lock debugging due to kernel taint\n");
280 set_bit(flag, &tainted_mask);
282 EXPORT_SYMBOL(add_taint);
284 static void spin_msec(int msecs)
286 int i;
288 for (i = 0; i < msecs; i++) {
289 touch_nmi_watchdog();
290 mdelay(1);
295 * It just happens that oops_enter() and oops_exit() are identically
296 * implemented...
298 static void do_oops_enter_exit(void)
300 unsigned long flags;
301 static int spin_counter;
303 if (!pause_on_oops)
304 return;
306 spin_lock_irqsave(&pause_on_oops_lock, flags);
307 if (pause_on_oops_flag == 0) {
308 /* This CPU may now print the oops message */
309 pause_on_oops_flag = 1;
310 } else {
311 /* We need to stall this CPU */
312 if (!spin_counter) {
313 /* This CPU gets to do the counting */
314 spin_counter = pause_on_oops;
315 do {
316 spin_unlock(&pause_on_oops_lock);
317 spin_msec(MSEC_PER_SEC);
318 spin_lock(&pause_on_oops_lock);
319 } while (--spin_counter);
320 pause_on_oops_flag = 0;
321 } else {
322 /* This CPU waits for a different one */
323 while (spin_counter) {
324 spin_unlock(&pause_on_oops_lock);
325 spin_msec(1);
326 spin_lock(&pause_on_oops_lock);
330 spin_unlock_irqrestore(&pause_on_oops_lock, flags);
334 * Return true if the calling CPU is allowed to print oops-related info.
335 * This is a bit racy..
337 int oops_may_print(void)
339 return pause_on_oops_flag == 0;
343 * Called when the architecture enters its oops handler, before it prints
344 * anything. If this is the first CPU to oops, and it's oopsing the first
345 * time then let it proceed.
347 * This is all enabled by the pause_on_oops kernel boot option. We do all
348 * this to ensure that oopses don't scroll off the screen. It has the
349 * side-effect of preventing later-oopsing CPUs from mucking up the display,
350 * too.
352 * It turns out that the CPU which is allowed to print ends up pausing for
353 * the right duration, whereas all the other CPUs pause for twice as long:
354 * once in oops_enter(), once in oops_exit().
356 void oops_enter(void)
358 tracing_off();
359 /* can't trust the integrity of the kernel anymore: */
360 debug_locks_off();
361 do_oops_enter_exit();
365 * 64-bit random ID for oopses:
367 static u64 oops_id;
369 static int init_oops_id(void)
371 if (!oops_id)
372 get_random_bytes(&oops_id, sizeof(oops_id));
373 else
374 oops_id++;
376 return 0;
378 late_initcall(init_oops_id);
380 void print_oops_end_marker(void)
382 init_oops_id();
383 printk(KERN_WARNING "---[ end trace %016llx ]---\n",
384 (unsigned long long)oops_id);
388 * Called when the architecture exits its oops handler, after printing
389 * everything.
391 void oops_exit(void)
393 do_oops_enter_exit();
394 print_oops_end_marker();
395 kmsg_dump(KMSG_DUMP_OOPS);
398 #ifdef WANT_WARN_ON_SLOWPATH
399 struct slowpath_args {
400 const char *fmt;
401 va_list args;
404 static void warn_slowpath_common(const char *file, int line, void *caller,
405 unsigned taint, struct slowpath_args *args)
407 disable_trace_on_warning();
409 pr_warn("------------[ cut here ]------------\n");
410 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
411 raw_smp_processor_id(), current->pid, file, line, caller);
413 if (args)
414 vprintk(args->fmt, args->args);
416 print_modules();
417 dump_stack();
418 print_oops_end_marker();
419 /* Just a warning, don't kill lockdep. */
420 add_taint(taint, LOCKDEP_STILL_OK);
423 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
425 struct slowpath_args args;
427 args.fmt = fmt;
428 va_start(args.args, fmt);
429 warn_slowpath_common(file, line, __builtin_return_address(0),
430 TAINT_WARN, &args);
431 va_end(args.args);
433 EXPORT_SYMBOL(warn_slowpath_fmt);
435 void warn_slowpath_fmt_taint(const char *file, int line,
436 unsigned taint, const char *fmt, ...)
438 struct slowpath_args args;
440 args.fmt = fmt;
441 va_start(args.args, fmt);
442 warn_slowpath_common(file, line, __builtin_return_address(0),
443 taint, &args);
444 va_end(args.args);
446 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
448 void warn_slowpath_null(const char *file, int line)
450 warn_slowpath_common(file, line, __builtin_return_address(0),
451 TAINT_WARN, NULL);
453 EXPORT_SYMBOL(warn_slowpath_null);
454 #endif
456 #ifdef CONFIG_CC_STACKPROTECTOR
459 * Called when gcc's -fstack-protector feature is used, and
460 * gcc detects corruption of the on-stack canary value
462 void __stack_chk_fail(void)
464 panic("stack-protector: Kernel stack is corrupted in: %p\n",
465 __builtin_return_address(0));
467 EXPORT_SYMBOL(__stack_chk_fail);
469 #endif
471 core_param(panic, panic_timeout, int, 0644);
472 core_param(pause_on_oops, pause_on_oops, int, 0644);
474 static int __init oops_setup(char *s)
476 if (!s)
477 return -EINVAL;
478 if (!strcmp(s, "panic"))
479 panic_on_oops = 1;
480 return 0;
482 early_param("oops", oops_setup);